Power toothbrush



FIG.

May 19, 1 970- T. TAYLO'R POWER 'TOOTHBRUSH Filed April 25, 1967 Wm;F167 :24 us INVENTOR. THEODORE L TAYLOR BY I 7 r I L f ..-M

ATTORNEY United States Patent 3,512,201 POWER TOOTHBRUSH Theodore L.Taylor, 4813 Woodburn Drive, Madison, Wis. 53711 Filed Apr. 25, 1967,Ser. No. 633,556 Int. Cl. A46b 13/02; A61c 17/00 US. Cl. 15-23 15 ClaimsABSTRACT OF THE DISCLOSURE A power toothbrush with dual motion brushhead. The primary motion is rotary, the head being driven by a motorthrough a gear train. The brush head shaft is also coupled to theplunger of a reciprocating solenoid. A timed rotary cam switch in themotor and solenoid circuits alternately closes and opens the circuits,so that the brush head rotates for a predetermined period, thenreciprocates for a short period. With the user pressing the brushbristles against the teeth or gingiva, the short stroke reciprocation ofthe head excites a vibratory bristle response, or vibrato, pressure onthe tips holding them stationary.

This invention relates to power toothbrushes, more particularly therotary brush head type. In its preferred form this invention employsdual brush heads.

Various motions have heretofore been proposed and used in powertoothbrushes. The principal motions are: reciprocating, oscillating,rotating. However, no single motion alone is entirely satisfactory forthe complete toothbrushing operation.

Reciprocation of bristle tips transversely of tooth faces and gingiva isgenerally undesirable, because continuous straight line motion of thetips across teeth and tissue may be severely injurious thereto. Suchaction may injure the tooth enamel, even cut grooves therein. Gingivitismay develop, and in any event, not only is brushing across the gingivahazardous, such action does not effectively clean under the gingiva, inthe crevices, or provide proper toning.

The most effective brush motion for general cleaning along the frontsand backs of the teeth is a rotary sweeping motion, beginning just abovethe gum line and continuing along the tooth face to the biting edge. Asimilar rotary or rocking motion is generally effective for cleaning thetops of molars and bicuspids. In the case of power toothbrushes, effortshave been made to simulate the desired action of the bristles by a rapidoscillatory motion of the brush head, with the intent that the user holdthe brush with its head shaft parallel to the gum line, the brush tipsthen sweeping back and forth across the faces of the teeth. However,this scheme has the serious disadvantage that for half of each cycle thebristle tips move in the wrong direction, that is, toward the gingiva,in large part nullifying the effectiveness of the. brushing action inthe other half cycle, the result being largely moving debris back andforth along the teeth rather than removing it. Furthermore, whenbrushing near or upon the gingiva, as is necessary for removal of debrisfrom beneath them and for toning, the reverse motion of the bristle tipsmay cause serious damage. Due to the relatively high speed at which apowered oscillating brush head operates, it is impossible to offset orameliorate the undesirable bristle action by manipulation.

Because of the foregoing objections to reciprocating and oscillatingbristle motion, a steady rotary brush head motion is preferable forcleaning tooth surfaces under power operation, with the bristle tipssteadily sweeping unidirectionally in an arcuate path. By providing areversible drive, the direction of rotation can be established asrequired for brushing up or down, or from right or left hand, asrequired for cleaning in the various areas. However, I find that forcleaning between teeth, even the rotary motion may often be largelyineffective, due to the tendency merely to force debris into thecrevices under pressure of the bristles, and without dislodgingparticles adhering tightly to tooth faces. These objections can beavoided or minimized by vibrating the bristles, with the bristle tipsheld stationary for a short period, the vibration loosening theparticles sufliciently, so that, upon resumption of the arcuate sweep,the particles will be removed, rather than pressed onto the teeth andinto the crevices.

It is a principal object of this invention to provide in a powertoothbrush a dual head motion, whereby most effectively to clean allsurfaces of the teeth and gums, as well as crevices, throughout themouth, with a minimum demand or reliance on manipulation by the user.

Another object of this invention is to provide in a dualmotion powertoothbrush, a control whereby automatically to cycle the brush headmotions with predetermined suitable periods of operation in each motion.

Yet another object of this invention is to provide a power toothbrushwhich is convenient to use and yet effects satisfactory, dependabletooth cleaning and gum massage with a minimum demand for manipulation bythe user.

The foregoing and other objects and advantages of the invention will beapparent upon reading the following description in conjunction with theaccompanying drawings, wherein:

FIG. 1 is a foreshortened side view of the toothbrush of this invention,with a portion of the case cut away to expose the drive and controlmechanisms therein;

FIG. 2 is a head end view of the brush assembly taken on line 22 of FIG.1;

FIG. 3 is a transverse section through the case on line 33 of FIG. 1;

FIG. 4 is a transverse section taken through the reciprocating driveplate on line 44 of FIG. 1;

FIG. 5 is an enlarged section on line 5-5 of FIG. 4, showing details ofconnection between reciprocating shafts and the reciprocating plate;

FIG. 6 is a circuit diagram showing the electrical system and apparatusfor driving and controlling the brush heads; and

FIG. 7 is a view showing a modified gear train for driving dual brushheads in the same direction of rotation.

Referring now to FIG. 1, reference numeral 10 indicates the case for thedrive and control elements, which case also serves as a handle. Case 10is provided with removable caps 11 and 12, which seal the case andpermit access for insertion and removal of the drive and controlcomponents. The caps may be fastened to the case in any suitable manner,for example, by means of dowels or screws (not shown).

V A gearmotor 14 is set into case approximately mid way thereof, with?an extended coaxial output shaft. 15 projecting toward cap 11. At itsouter end shaft 15 carries a wide-faced spur gear 16. In order tominimize bendingload and whip of shaft 15, and for anotheripurpose laterto be described, a support plate 17 is provided about midway of theshaft extension, having a close-fitting central aperture 18, throughwhich the shaft 15 extends.

Gearmotors such as that here illustrated are, well-- known, andcommercially available. Therefore, detailed description thereof is notnecessary here. Gearmotor 14 is selected for an output shaft speed whichis best suited to producing the desired brush head speed through anassociated drive train which meets the space imitations and efficiencyrequirements for the particular combination. In the embodiment hereillustrated gearmotor shaft speed of 500 r.p.m. is desirable, involvinga 7/1 reduction unit in gearmotor 14 from synchronous full load motorspeed on 60-cycle-AC power supply. Gearmotor units having other outputspeed and/or reduction ratios are available or readily made inaccordance with well known practices, as may be required for other powersupply rive trains and ultimate brush-head speed.

The example here illustrated involves driving twin rotary brush heads 19and 20 through twin drive shafts 21 and 22, which at their inner endsare journalled in support plate 17 parallel to and alongside gearmotorshaft 15. Shafts 21 and 22 carry spur gears 23 and 24 in mesh, gear 24in turn meshing with gear 16 on output shaft 15. A solenoid 25 ismounted on motor face plate 26 alongside output shaft 15, with thereciprocating solenoid output shaft 27 midway between drive shafts 21and 22, shaft 27 extending through support plate 17.

As best seen in FIG. 2, brush heads 19 and 20 are of the same outsidediameter. For uniform cleaning action both brush heads preferably rotateat the same speed. Therefore, the gears 23 and 24 are preferably meshedin 1/ 1 ratio, as best seen in FIG. 3. As will be apparent frominspection of FIG. 1, the diameter of gears 23 and 24 is a function ofthe diameters of brush heads 19 and 20, which in turn are primariiydetermined by considerations of dental structure and accessibility inthe oral cavity, together with" the requirement of providing a brushdrive and case which are as simple, safe and convenient as possible. Inthe arrangement illustrated here it is found that gear 16 need besomewhat larger in diameter than gears 23 and 24, whereby brushes 19 and20 rotate at a speed somewhat greater than that of gearmotor drive shaft15. For example, with 500 r.p.m. for shaft 15, brushes 19 and 20 rotateat 1000 r.p.m. With brush heads approximately 4 inch in outsidediameter, which I have found to be a suitable size, the bristle tipspeed is about 13 i.p.s., substantially an optimum cleaning speed fromthe standpoints of safety and effectiveness.

Referring again to FIG. 1 and also to FIG. 4, an elliptical bridge piece28 spans drive shafts 21 and 22, apertures 29 and 30 being slightlylarger than the diameter of shafts 21 and 22, so that the latter mayrotate freely with respect to bridge 28 when driven by gearmotor 14.Solenoid shaft 27 extends through apterture 31 in bridge 28. Ferrules orwashers 32 are aifixed to shafts 21, 22 and 27 in position to constituteflanges on both sides of the bridge 28 along each of the shafts. Thus,when solenoid 25 is energized, brush shafts 21 and 22 will reciprocatewith solenoid plunger 27, gears 23 and 24 remaining in mesh and gear 24remaining in mesh with drive gear 15, the latters face being somewhatwider than that of gear 24 to insure full engagement in any axialposition of the latter within the stroke range, and with allowance fornormal variations in assembly.

Operation of the gearmotor 14 and solenoids 25 is controlled by means of(l) a manual switch 33, conveniently located in the wall of case 10 at aposition readily accessible to the users thumb when gripping the casefor comfortable manipulation of the brush assembly, (2) a timer 34, withrotary contactor 35, in the rear of case 10, behind gearmotor 14, and(3) interlocking electric circuitry, best seen in the block wiringdiagram in FIG. 6. Terminals T and T indicate the prongs of theconventional electrical plug in circuit through an external switch 33,such as a toggle switch, serving as a safety switch, permitting thebrush to be left plugged in, but guarding against accidentallyenergizing the brush mechanism while handling the unit when not inactual use. Closing of the switch 33 at T connects T to timer 34 at Tand to one leg of contractor 35'at T T on the other leg of contactor 35is connected to solenoid 25 at T The other leg of contactor 35 isconnected from T to T on one throw of switch 13 and to T on the otherthrow of switch 13.

Input terminal T is directly connected to T of timer 34, T of solenoid25, T on one throw of switch 13 and T on the other throw of switch 13.

Throw-arm double-contactor 37 of switch 13 is directly connected throughT and T to terminals T and T respectively of gearmotor 14.

T and T are on a winding of gearmotor 14 for operation in one directionof rotation, while T and T are on a winding of gearmotor 14 foroperation in the opposite direction of rotation. Therefore, throwingswitch arm 37 in one direction establishes a winding circuit for forwardmotor operation and throwing the arm in the other direction establishesa winding circuit for reverse rotation. However as previously noted, oneswitch pole on each motor winding circuit is connected through ro tarycontactor 35 on shaft 38 timer 34. Contactor 35 is of the rotary,wiping-cam type, well-known in the timer art, thus not requiringdescription herein detail. The wiper cam 39 is in this case selected toestablish circuit between T and T during a portion of a revolution andbetween T and T during the balance of a revolution. The are of contactis selected to establish the relative portions of the revolution in eachcircuit contact, while the speed of the timer 34 determines the periodof contact in each circuit, contact to T energizing gearmotor 14 andcontact to T energizing solenoid 25, while cutting off gearmotor 14.

When solenoid 25 is energized, brush heads 19 and 20 reciprocate byvirtue of the arrangement previously described. The stroke of solenoidplunger 27 is preferably quite short, on the order of A to 4;", asdetermined by the selection of solenoid winding and armature accordingto well-known principles. With the user holding the brush bristlesfirmly against the teeth in the normal rotary cleaning operation of theheads 19 and 20, the introduction of reciprocating motion, while cuttingoff the rotary motion, will cause the bristles to vibrate in thedirection of the solenoid plunger stroke, the stroke being so short thatthe tips of the bristles do not move, pressure against the teethprecluding tip motion. This action may aptly be termed vibrato. I findthat this vibrato action is extremely effective in loosening particlesof debris, particularly in the crevices, whereafter resumption of rotaryhead motion sweeps the debris from the teeth and out of the crevices.Assuming a total brushing time of 30 seconds in a given region withoutsubstantial translation of the brush heads, about 7-8 seconds is adesirable portion of the total brushing time in one region for vibratoaction. Therefore, timer 34, of the usual geared type, is selected for ashift speed of 2 r.p.m., with motor contact during of each revolutionand solenoid contact during the other 25% of each revolution. However,it will be obvious that the timer and contactor can be selected invarious combinations for other time cycles, such timers and contactorsbeing available in a wide variety of combinations.

Referring again to FIG. 1, the extended portions of shafts 21 and 22,beyond cap 11, are journalled in sleeve 40, which is generallyelliptical in cross-section, as best seen in FIG. 2, bafiles 41, 42supporting the shaft extensions to minimize whip and undesirable lateralvibration. An inner end portion of housing 40 extends through aperture43 in cap 11, hearing on wall 44 of aperture 45 in bushing 46, while theinner end portion of baffle 42 extends through aperture 43 and bears onwall 47 thereof, anchoring the shaft housing assembly against accidentaldislodgement or shift. It will be understood that brush heads 19 and 20may be splined or otherwise removably coupled to shafts 21 and 22, tofacilitate replacement of worn brushes, or interchange for hygenicreasons, if the unit is to be used by several persons. Means for suchremovable brush attachment are well known in the art and therefore nothere illustrated or described in detail.

A lip and cheek guard 48 is preferably provided adjacent brush heads 19and 20, so that the bristles thereof will not inadvertently scrape softoral tissues. Guard 48 is preferably made of semi-flexible material, toconform comfortably in the oral cavity in various brushing positions,and may be shiftably clipped to housing 40, whereby to provide forreversal of brush exposure when cleaning on opposite sides of the teeth,or changing hand.

The gear drive above described is adapted to rotate the brush heads inopposite directions. This arrangement is slightly disadvantageous forbrushing behind the teeth, since, with the opening necessary for theholder, the heads must be moved up and down to reach uppers and lowers,only one brush being operative at a given instant. If desired, thebrushes can be geared for rotation in the same direction by use of anidler gear, as shown in FIG. 7, wherein parts corresponding to those ofprevious drawings are correspondingly numbered, with the addition of100. Drive gears 123 and 124 are here separated, gear 124 being meshedwith gear 116, on gear motor shaft 115. Idler gear 150 is interposed inmesh with gears 123 and 124, on brush head shafts 121 and 122, so thatthe latter rotate in the same direction, as indicated by the arrows. Theidler gear shaft 151 may be mounted on plate 17 -(FIG. 1), just belowbridge piece 28. With the brush heads rotating in the same direction,both brushes are applied to the same line of teeth at one time, oneoperating on or near the gingiva, the other toward the tooth edges. Insuch case one brush in effect feeds debris to the other, providing aconveyor action.

With either brush drive arrangement, the reversing switch 13, indicateddiagrammatically in FIG. 6, may be conveniently incorporated into thecap 11, in the form of a rotary switch having contactors for forward,off and reverse motor conditions, as previously described. A suitablelocation of switch 13, in thearrangement shown in FIG. 1, is between cap11 and case 10, as indicated generally by the reference numeral 13.Switch structures of this type are well-known inthe electrical appliancearts, as used on mixers, blenders, fans and other multi-speedappliances. In this instance, suitable indicia may be provided on thecap 11 and adjacent portion of case 10. The user can readily positionthe cap and switch 13 for selected motor condition by turning the capwith thumb and index finger, while holding case with the palm or theother hand. However, other switch arrangements may be used, as desiredfor particular convenience, economy or styling requirements.

I claim and desire to secure by Letters Patent the following:

1. A power toothbrush comprising: a case, a brush shaft extending fromsaid case, first drive means including a first motor associated withsaid brush shaft for rotation thereof, second drive means including asecond motor associated with said brush shaft for reciprocation thereof,and control means associated with both said drive means for alternatingmotion of said brush shaft between rotation and reciprocation.

2. A power toothbrush comprising: a case, a brush shaft extending fromsaid case, first drive means associated with said brush shaft forrotation thereof, second drive means associated with said brush shaftfor reciprocation thereof, and control means associated with both saiddrive means for alternating motion of said brush shaft between rotationand reciprocation, said first drive means including a motor having anoutput shaft parallel to said brush shaft and a gear train through whichsaid output shaft drives said brush shaft when said motor is energized.

3. A power toothbrush according to claim 2, said motor being reversible,further including a control for selected operation of said motor ineither direction of rotation.

4. A power tooth brush according to claim 2, wherein said control meansincludes a timer and a contactor associated with said timer, saidcontactor being arranged in circuit with elements of said first and saidsecond drive means alternately to energize said elements forpredetermined periods of operation, according to selected settings ofsaid contactor and said timer.

5. A power toothbrush according to claim 4, wherein said contactorincludes arcuate legs and a rotary wiper contacting said legs, saidwiper being driven by said timer, at least one of said legs beingbi-segmental, with a first segment in circuit with an element of saidfirst drive means and a second segment in circuit with an element ofsaid second drive means.

6. A power toothbrush comprising: a case, a pair of closely parallelbrush shafts extending from said case, normally rotary brushes onextensions of said brush shafts, first drive means arrangedsimultaneouly to rotate said brush shafts at predetermined speed, seconddrive means arranged simultaneously to reciprocate said brush shafts atpredetermined speed and stroke, and control means alternately energizingan element in each of said first and second drive means.

7. A power toothbrush according to claim 6, wherein said first drivemeans'includes a gearmotor having an output shaft parallel to said'brush shafts, a gear on said output shaft, and a gear train meshed withsaid output shaft gear, said train including gears on said brush shafts;and said second drive means includes a solenoid having its plungercoupled to said brush shafts.

8. A power toothbrush according to claim 7, wherein said plunger isparallel to said brush shafts and coupled thereto by a bridge piece,each said brush shaft being engaged with said bridge piece by meansjournalling said brush shafts for rotation independently of said bridgepiece.

9. A power toothbrush according to claim 8, wherein said brush shaftgears mesh with each other for rotation of said brush shafts in oppositedirections.

10. A power toothbrush according to claim 8, wherein said brush shaftgears are spaced transversely of said brush shafts, an idler gear meshedwith both said brush shaft gears causing said brush shafts to rotate inthe same direction.

11. A power toothbrush according to claim 6, wherein said first drivemeans includes a motor and said second drive means includes a solenoid,said motor and said solenoid being in energizing circuits connected tosaid control means.

12. A power toothbrush according to claim 11, said motor beingreversible, and further including a control for selected operation ofsaid motor in either direction of rotation.

13. A power toothbrush according to claim 11, wherein said first driveelement is a motor and said second drive element is a solenoid, saidcontrol means including a timer and a contactor associated with saidtimer, said contactor being arranged in circuit with said motor and saidsolenoid alternately to energize said motor and said solenoid, each fora predetermined period, according to predetermined settings of saidcontactor and said timer.

14. A power toothbrush according to.claim 13, wherein said contactorincludes arcuate legs and a rotary wiper contacting said legs, saidWiper being driven by said timer at predetermined speed, at least one ofsaid legs being bi-segmental, said one leg having a first segment incircuit with said motor and a second segment in circuit with saidsolenoid.

15. A power toothbrush comprising: a case; a reciprocable and rotatablebrush shaft extending from said case; drive means including electricmotor means associated with said shaft, said motor means being selec- 1tively operable in reciprocating or rotary motion to correspondinglyreciprocate or rotate said shaft; and electric control means operable toselect one or the other said motion of said motor means.

References Cited UNITED STATES PATENTS 2,124,145 7/1938 Merkel 15232,858,701 11/1958 Willcox.

3,104,347 9/1963 Dresen 15-23 X 3,235,897 2/1966 Fortenberry 1524FOREIGN PATENTS 953,255 5/ 1949 France.

EDWARD L. ROBERTS, Primary Examiner US. Cl. X.R. 1522; 51170

